Weak, sprawling stems, up to 3 ft. long, are armed with hooked prickles. Bi-pinnately compound leaves, having an airy appearance. The leaflets are sensitive to the touch if one brushes against them or touches them, they immediately fold up against each other, suggesting the name sensitive briar. They also close at night and in cloudy weather. The fragrant flowers look like small pink balls and grow along the stem at varying intervals. They have 4 or 5 sepals, 4 or 5 united petals, 8–10 pink or rose-purple stamens, and 1 pistilFlower heads occur on stalks from leaf axils. The fruit is a long, slender pod, densely covered with prickles.

Smooth-leaf Sensitive-brier is a member of the pea family (Fabaceae), which includes trees, shrubs, herbs, and vines with compound or occasionally simple leaves and flowers usually in clusters.